Coal pyrolysis tar recovery method and system

Abstract

The invention relates to a coal pyrolysis tar recovery method and system.The method comprises the steps that oil mist and raw coke oven gas are introduced into a washing tower, the oil mist, the raw coke oven gas and washing oil make direct contact for cooling and separation, liquid-phase coal tar and a gas-phase medium are obtained, the gas-phase medium is subjected to two-stage cooling through an air cooler and a condenser in sequence, then oil-water separation is conducted, and the gas-phase medium is recycled; the method comprises the following steps: finely filtering liquid-phase solid-containing coal tar from outside to inside by adopting a 0.1-micron metal sintered film-coated filter element under the conditions of 260-280 DEG C and 1.0-1.2 MPa, discharging filter residues through a pressurized residue discharge valve, and carrying out vacuum fractionation on the solid-removed coal tar to recover wash oil and clean tar. By controlling the cooling temperature of the liquid-phase coal tar at 110-120 DEG C and adopting specific filtering parameters, high-efficiency removal of micron-sized solid particles in the high-temperature viscous medium is realized. The method is suitable for efficient recovery of coal pyrolysis tar, the obtained washing oil can be recycled, and the clean coal tar can be directly used as fuel or a chemical raw material.

Description

Technical Field

[0001] The present invention relates to the field of coal pyrolysis, and more specifically, to a method and system for recovering tar from coal pyrolysis. Background Art

[0002] Coal pyrolysis technology is the core driving force for the efficient utilization of coal. Solving the pain points in each link of the entire process of coal pyrolysis technology is a breakthrough in promoting the development of coal pyrolysis technology and forming coordinated development of the upstream and downstream of the industrial chain.

[0003] Coal tar is one of the important products of coal pyrolysis. As a high value-added oil product, its deep processing mainly uses hydrogenation equipment to produce light fuels (such as gasoline and diesel), which can greatly improve economic benefits. At present, the cooling method after coal pyrolysis is water washing. The coal pyrolysis temperature is 600~800℃, and a large amount of water is consumed during cooling. In addition, a large amount of water vapor is also generated during the pyrolysis process. The cooled coal tar contains a large amount of water and organic matter such as phenols. Some organic matter is weakly acidic and corrodes equipment in long-term operation. The existing technology cannot completely purify the organic matter in the water after extraction or oil-water separation, especially phenols cannot be separated, which will lead to the discharge of a large amount of polluted water, greatly damaging the environment.

[0004] Coal tar contains a large amount of solid particles and has high viscosity. Solid sedimentation during transportation can cause pipeline blockage and other problems. At present, coal tar solid removal technology basically adopts centrifugation, sedimentation or adding agents, but the removal rate of coal tar solid particles is not high, especially some particles below 5 microns. The existing filtration device is blocked and cannot operate after three months due to poor filter element regeneration effect. Failure to achieve the removal rate will cause catalyst coking in the downstream hydrogenation unit, reduce activity, increase pressure drop, and the unit cannot operate for a long period of time. Therefore, coal tar solid removal technology is a key process that restricts the sustainable development of the current industrial chain and needs to be solved urgently. Summary of the invention

[0005] The object of the present invention is to provide a method and system for recovering coal pyrolysis tar, so as to at least solve the above-mentioned problems.

[0006] In order to achieve the purpose and other advantages of the present invention, a method for recovering tar from coal pyrolysis is provided, comprising the following steps: pyrolyzing coal at high temperature in a reactor to generate coke, oil mist and raw coal gas; passing the oil mist and raw coal gas into a washing tower, so that the oil mist and raw coal gas are in direct contact with washing oil for cooling, and liquid coal tar and gaseous medium are separated; cooling the gaseous medium in turn through a primary cooling process of an air cooler and a secondary cooling process of a condenser, and then performing an oil-water separation process to obtain low-boiling point organic matter and purified water; conveying the liquid coal tar to a filter for filtration to remove solid particles; the desolidified coal tar enters a washing oil vacuum tower for fractionation, and the washing oil vapor produced at the top of the tower is recovered to a washing oil storage tank after condensation, and the clean coal tar at the bottom of the tower is conveyed to a coal tar storage tank or a downstream device; Among them, the temperature of the liquid-phase coal tar after cooling is controlled at 110 - 120 °C; the filter uses a metal sintered membrane filter element with a pore size of 0.1 μm. The operating temperature of the filter is 260 - 280 °C, and the operating pressure is 1.0 - 1.2 MPa. The filtration operation includes: transporting the solid-containing coal tar at the bottom of the tower to the filter, and filtering from the outside to the inside through the metal sintered membrane filter element. When the solid accumulation on the surface of the metal sintered membrane filter element reaches the set thickness, the space above the tube sheet of the filter is pressurized to the set pressure value, and then the slag discharge valve is opened to discharge the solid particles accumulated on the surface of the metal sintered membrane filter element to the downstream slag receiving tank.

[0007] Preferably, the reaction furnace adopts a vertical continuous pyrolysis reaction furnace; before the coal enters the reaction furnace, it is first subjected to screening and crushing treatment to control the particle size range of the coal particles between 5 - 20 mm, and then the screened and crushed coal is evenly fed into the reaction furnace through a sealed feeding device at a feeding speed of 5 - 15 tons per hour; the high-temperature pyrolysis process in the reaction furnace is divided into three stages: preheating stage: high-temperature gas is sprayed at the bottom of the reaction furnace through a burner to raise the temperature in the furnace from room temperature to 200 - 300 °C within 10 - 15 minutes, and the moisture and some volatile substances in the coal begin to precipitate; rapid pyrolysis stage: after the preheating stage ends, the gas supply is increased to rapidly raise the temperature in the furnace to 500 - 600 °C within 20 - 30 minutes, and at the same time, the stirring device in the reaction furnace is started to rotate at a speed of 15 - 20 revolutions per minute, continuously turning the coal particles to ensure uniform heating of the coal. At this time, the coal undergoes a violent pyrolysis reaction, and a large amount of oil mist and raw gas are generated; deep pyrolysis stage: after the rapid pyrolysis stage ends, the gas supply is reduced to keep the temperature in the furnace at 600 - 800 °C for 30 - 40 minutes, so that the organic substances in the coal are fully pyrolyzed to generate more coke, oil mist and raw gas.

[0008] Preferably, the washing tower uses circulating wash oil as the cooling medium. The circulating wash oil is led out from the wash oil storage tank and transported to the washing tower by a wash oil pump for direct contact countercurrent cooling of the oil mist and raw gas. The initial boiling point of the wash oil is 230 - 300 °C; a flow regulating valve is provided at the wash oil inlet of the washing tower, and the flow rate of the wash oil entering the washing tower is controlled by adjusting the opening of the flow regulating valve; the specific method for controlling the temperature of the liquid-phase coal tar after cooling at 110 - 120 °C is: a first temperature sensor is provided at the liquid-phase coal tar outlet of the washing tower, and the first temperature sensor is connected to the control system. When the first temperature sensor detects that the temperature of the liquid-phase coal tar is higher than 120 °C, the control system controls the flow regulating valve to increase the opening to increase the flow rate of the wash oil entering the washing tower and enhance the cooling effect; when the first temperature sensor detects that the temperature of the liquid-phase coal tar is lower than 110 °C, the control system controls the flow regulating valve to decrease the opening to reduce the flow rate of the wash oil entering the washing tower and reduce the cooling effect.

[0009] Preferably, a spiral plate condenser is used, and its cooling medium is a mixed medium of circulating cooling water and chilled water; a second temperature sensor is provided on the condenser outlet pipe to monitor the temperature T of the gas-phase medium after cooling in real time. c , and the opening degree of the chilled water proportion regulating valve is dynamically adjusted through the control system to make T c stable in the range of 50 - 60 °C; the oil-water separation treatment adopts a three-stage coalescence separation device, which is internally provided with a hydrophobic and oleophilic fiber packing layer and a corrugated plate coalescence component; the control system is configured with a temperature-viscosity compensation module. When it is detected that T c > 60 °C, the electric field strength of the three-stage coalescence separation device is adjusted to 2 - 3 kV / cm, and the pressure in the separation chamber is controlled to be 0.05 - 0.1 MPa.

[0010] Preferably, the hydrophobic and oleophilic fiber packing layer is designed with a gradient density structure and is divided into three layers from top to bottom. The top layer is a polytetrafluoroethylene fiber woven mesh with a pore diameter of 8 - 12 μm and a porosity of 85% - 90%. The middle layer is a polypropylene fiber bundle coated with a nano-silica coating, and the fiber spacing is 0.3 - 0.5 mm. The bottom layer is a three-dimensional corrugated structure composed of a composite weave of carbon fiber and glass fiber, and the corrugation inclination angle is 45° - 60°; the plate spacing of the corrugated plate coalescence component is 10 - 15 mm, and the surface is provided with a micro-groove array with a depth of 0.2 - 0.3 mm, and the direction of the micro-grooves forms a 30° angle with the direction of the medium flow.

[0011] Preferably, when the thickness of the solid accumulation on the surface of the metal sintered membrane filter element reaches 3 - 5 mm, high-pressure nitrogen is introduced into the space above the filter tube sheet to pressurize the space above the filter tube sheet. When the pressure reaches the set value, the downstream quick-opening backwashing slag discharge valve is opened. Under the action of the pressure difference, the solid particles on the surface of the metal sintered membrane filter element quickly detach from the metal sintered membrane filter element. After the inside of the filter is drained, the quick-opening backwashing slag discharge valve is closed to complete the regeneration process of the metal sintered membrane filter element.

[0012] Preferably, the desolidified coal tar is continuously fed into the middle feed port of the wash oil vacuum tower through a screw conveyor preheated to 210 - 230 °C. Four fractionation sections are arranged in the wash oil vacuum tower, which are, from top to bottom, the light wash oil capture section, the main fractionation section, the heavy fraction buffer section, and the bottom heat circulation section; the light wash oil capture section operates at an absolute pressure of 15 - 25 kPa, with three layers of inclined baffle trays inside, and a microporous distributor with a pore diameter of 0.8 - 1.2 mm is provided on the tray surface. The top temperature of the light wash oil is controlled at 85 - 95 °C through an external condenser; the main fractionation section is filled with regularized stainless steel corrugated packing, and the specific surface area of the packing is 450 - 500 m² / m³. A distributed temperature sensor array is arranged in the main fractionation section to monitor the axial temperature gradient in real time and feedback to adjust the pressure at the top of the vacuum tower, so that the temperature gradient is maintained at 12 - 15 °C / m; the bottom heat circulation section is equipped with a dual-channel heat medium heating system, in which the main channel uses heat transfer oil circulation heating to maintain the bottom temperature at 195 - 205 °C, and the auxiliary channel dynamically compensates for temperature fluctuations through a steam ejector. When it is detected that the bottom viscosity exceeds 300 mPa·s, the steam ejector is automatically started to reduce the viscosity.

[0013] Preferably, after the wash oil vapor is taken out from the top of the wash oil vacuum tower, it first enters the primary condenser for indirect heat exchange with circulating cooling water at 30 - 40 °C, so that the temperature of the wash oil vapor is reduced to 80 - 90 °C; then it enters the secondary condenser for countercurrent heat exchange with chilled brine at 5 - 10 °C in a spiral tube process, and the wash oil vapor is further cooled to 40 - 50 °C and completely liquefied and then transported to the wash oil storage tank; among them, the primary condenser adopts a corrugated plate fin structure, and the heat transfer surface is coated with a graphene - titanium dioxide composite anti - coking coating; the inner wall of the spiral tube process of the secondary condenser is provided with spiral microchannels with a depth of 0.3 - 0.4 mm and a channel spacing of 2 - 3 mm.

[0014] The present invention also provides a coal pyrolysis tar recovery system, which is used to implement the above - mentioned coal pyrolysis tar recovery method.

[0015] The present invention has at least the following beneficial effects: First, by adopting the direct contact countercurrent cooling of wash oil with oil mist and raw coal gas, and controlling the liquid-phase coal tar cooling temperature at 110 - 120 °C, this temperature setting can, firstly, avoid the liquefaction of a large amount of water vapor generated during the pyrolysis process, separate low-boiling organic substances and water vapor in the gas phase from coal tar. When the subsequent condensation temperature is controlled at 50 - 60 °C, pollution-free discharge of water can be achieved through oil-water separation. Secondly, wash oil can be used as a solvent for coal tar to dissolve substances with high viscosity such as asphaltene in coal tar, so as to reduce the viscosity of coal tar, enabling the subsequent filtration system to achieve liquid-solid separation and operate in a long cycle. Filtration from the outside to the inside is carried out using a 0.1-micron metal sintered membrane filter element at 260 - 280 °C and 1.0 - 1.2 MPa, combined with the operation of pressurized slag discharge, which can effectively intercept submicron solid particles (such as coke powder and carbon black). At the same time, the viscosity of tar is reduced by high temperature to reduce the adhesion on the surface of the filter element, significantly improving the filtration efficiency, and the solid content of the purified coal tar is not more than 50 ppm. The segmented pressurized slag discharge design realizes cake stripping by dynamically adjusting the pressure difference, avoiding the residual problem of traditional gravity slag discharge, extending the service life of the filter element to more than 2000 hours, and reducing the filtration accuracy attenuation rate to less than 2% per month. Compared with the method of separating coal tar solids by adding chemicals, this method is purely physical, avoiding the impact on downstream catalysts caused by adding chemicals, and greatly reducing the operating costs and energy consumption at the same time.

[0016] Second, a vertical continuous pyrolysis reaction furnace is adopted and the temperature is controlled in stages (preheating, rapid pyrolysis, and deep pyrolysis). Combining the control of coal particle size and uniform feeding can make the coal particles heat more evenly, reducing the phenomena of coking or insufficient pyrolysis caused by local overheating. The coal bed is turned over by a stirring device at 15 - 20 revolutions per minute, effectively breaking the material adhesion layer formed during the pyrolysis process, and increasing the release rate of oil mist and raw coal gas by 15% - 20%. The staged heating strategy (preheating at 200 - 300 °C, rapid pyrolysis at 500 - 600 °C, and deep pyrolysis at 600 - 800 °C) matches the kinetic characteristics of coal pyrolysis, stabilizing the coke yield at 65% - 70%, and simultaneously reducing the content of non-target components such as CO in the raw coal gas to less than 5%.

[0017] Third, through the joint control of the first temperature sensor and the flow regulating valve, combined with the reasonable selection of the initial distillation point of wash oil (230 - 300 °C), high-boiling tar components can be preferentially condensed during the cooling process, reducing the escape of light oil mist.

[0018] Fourth, the spiral plate condenser is combined with a mixed cooling medium (circulating water + chilled water), and the proportion of chilled water is adjusted through the fourth temperature sensor, so that the temperature of the gas phase medium is stabilized in the range of 50-60°C after cooling, and the condensation efficiency of low-boiling organic matter is increased to 98.5%. The three-stage coalescence separation device adopts electric field enhancement (2-3kV / cm) and pressure coordinated regulation, and the separation efficiency of oil droplets with a particle size of >5μm reaches 99.9%, and the oil content of the outlet water is <50mg / L. The temperature-viscosity compensation module effectively suppresses the oil-water emulsification phenomenon at high temperature by adjusting the separation chamber pressure (0.05-0.1MPa) in real time, and the COD value of the wastewater is reduced to below 3000mg / L.

[0019] Fifth, the gradient density hydrophobic and oleophilic filler layer intercepts large-size oil droplets through the top PTFE fiber mesh (porosity 85%-90%), the middle layer of nano-SiO2 coated polypropylene fiber bundles (spacing 0.3-0.5mm) adsorbs submicron oil mist, and the bottom three-dimensional corrugated structure (inclination angle 45°-60°) prolongs the oil-water contact time, and the comprehensive separation efficiency is improved by 12%-15%. The corrugated plate micro-groove array (0.2-0.3mm deep, 30° angle) induces droplet collision and coalescence, increasing the average particle size of oil droplets from the initial 50μm to more than 300μm, and the coalescence time is shortened to 1 / 3 of that of traditional fillers. The carbon fiber-glass fiber composite structure can withstand temperatures of up to 150°C, and its service life is extended to more than 5 years.

[0020] The design of the sixth and fourth distillation sections is combined with the decompression operation (15-25kPa), which increases the separation efficiency of wash oil and heavy component tar to 99.2%, and the content of heavy components (>300℃) in the wash oil is ≤0.5%. The structured packing (450-500m² / m³ specific surface area) and distributed temperature monitoring work together to achieve an axial temperature gradient control accuracy of ±0.5℃ / m, and the distillation range of the wash oil (initial distillation point-dry point) is narrowed to within 20℃. The dual-channel heating system (thermal oil + steam injection) stabilizes the bottom viscosity at 200-250mPa·s, the steam injection compensation response time is ≤10 seconds, and the thermal cycle energy consumption is reduced by 18%.

[0021] Seventh, the two-stage condenser graded cooling (80-90℃→40-50℃) combined with graphene-titanium dioxide anti-coking coating makes the washing oil vapor condensation efficiency reach 99.8%, and the coking rate is reduced to below 0.1g / (m²·h). The spiral micro-grooves (0.3-0.4mm deep, 2-3mm spacing) enhance the turbulent effect, increase the heat transfer coefficient to 3500W / (m²·K), and reduce the amount of frozen brine by 25%. The water content of the fully liquefied washing oil is less than 0.1%, which can be directly reused in the washing tower, and the annual recycling rate is ≥99.5%.

[0022] Other advantages, objects, and features of the present invention will be partly reflected by the following description, and partly will be understood by those skilled in the art through the research and practice of the present invention. Brief Description of the Drawings

[0023] Figure 1 is a schematic flow chart of a method for recovering coal pyrolysis tar in an embodiment of the present invention.

[0024] Figure 2 is a schematic connection structure diagram of a coal pyrolysis tar recovery system in another embodiment of the present invention. Detailed Embodiments

[0025] The present invention will be further described in detail below in conjunction with embodiments and the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0026] It should be understood that terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0027] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can all be obtained from commercial channels unless otherwise specified; in the description of the present invention, the orientation or positional relationship indicated by terms such as "horizontal", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention.

[0028] Such as Figure 1As shown in the figure, in one embodiment of the present invention, a method for recovering coal pyrolysis tar is provided, which includes the following steps: pyrolyzing coal at high temperature in a reaction furnace (the reactor in the figure) to generate coke, oil mist and raw gas; introducing the oil mist and raw gas into a washing tower, directly contacting the oil mist, raw gas with wash oil for cooling, and separating to obtain liquid-phase coal tar (coal tar in the figure) and gas-phase medium (water vapor and low-boiling organic compounds in the figure); after the gas-phase medium is cooled by an air cooler at the first stage and a condenser at the second stage in sequence, performing oil-water separation treatment to obtain low-boiling organic compounds and purified water; transporting the liquid-phase coal tar to a filter to filter and remove solid particles; the coal tar after solid removal enters a wash oil vacuum tower for fractionation, the wash oil vapor is taken out from the top of the tower, condensed and then recycled to the wash oil storage tank, and the net coal tar at the bottom of the tower (clean coal tar in the figure) is transported to the coal tar storage tank or downstream device; wherein, the temperature of the liquid-phase coal tar after cooling is controlled at 110-120°C; the filter uses a metal sintered membrane filter element with a pore size of 0.1 micron, the operating temperature of the filter is 260-280°C, the operating pressure is 1.0-1.2 MPa, and the filtering operation includes: transporting the solid-containing coal tar at the bottom of the tower to the filter, filtering from the outside to the inside through the metal sintered membrane filter element, when the solid accumulation on the surface of the metal sintered membrane filter element reaches the set thickness, pressurizing the space above the filter tube sheet to the set pressure value, and then opening the slag discharge valve to discharge the solid particles accumulated on the surface of the metal sintered membrane filter element to the downstream slag receiving tank (slag filter tank in the figure), the mixture in the slag receiving tank is a mixture of solid particles and wash oil, and the wash oil can be separated from the mixture in the slag receiving tank in a downstream flash tank, and the solid enters a dryer for drying.

[0029] In the above technical solution, the specific value of the cooling temperature of the liquid-phase coal tar can be set to 112°C, 115°C or 118°C, and the temperature control accuracy is ±2°C. The washing tower can be a packed tower with a diameter of 3.2 meters and a height of 18 meters, filled with 50mm metal Pall rings, and a wash oil distributor is arranged at the top of the tower. The temperature control is achieved by adjusting the wash oil circulation rate, and the wash oil can be an anthracene oil fraction with a flash point of 230°C. A liquid level gauge and a temperature sensor linkage control system are arranged at the bottom of the washing tower. When the liquid phase temperature exceeds 120°C, the wash oil spray amount is automatically increased. The supporting wash oil circulation pump can be an IH type chemical centrifugal pump with a motor power of 55kW. In the above technical solution, the filtration accuracy of the metal sintered membrane filter element can be selected as 0.1 micron, the filter element matrix material can be selected as 316L stainless steel, and the surface coating can be selected as 316L stainless steel. The filter housing can be selected as Q345R or chrome molybdenum steel, with a design pressure of 1.5 MPa, and is installed in the horizontal section after the elbow of the bottom outlet pipeline of the washing tower. The filtration pressure is adjusted by a pressure reducing valve, and the pressure transmitter can be selected as Rosemount 3051 type, with a range of 0-2.5 MPa, and is installed at the top of the inlet pipeline of the filter. Similar equipment configurations can be seen in the catalytic cracking slurry filtration system in the petrochemical industry. In the above technical solution, the pressure setting value for pressure-assisted slag discharge can be selected as 1.3 MPa, 1.5 MPa or 1.7 MPa, and nitrogen can be used as the pressure-assisted medium. The slag discharge valve can be a ball valve or a triple-eccentric butterfly valve. The valve body material can be WCB and is installed at the flange of the slag discharge port at the bottom of the filter. The differential pressure trigger threshold is set at 0.35 MPa, and the differential pressure between the inside and outside of the filter element is monitored in real time through a differential pressure transmitter (range 0 - 0.6 MPa). The slag discharge duration can be set at 45 seconds, 60 seconds or 75 seconds, and the valve is closed after the slag discharge is completed. A similar slag discharge method can refer to the automatic backwashing design of the coal chemical black water filtration system. Through the above implementation method, the temperature fluctuation range of the liquid-phase coal tar cooling is reduced from ±10 °C to ±2 °C. The metal sintered membrane filter element has an interception efficiency of 99.8% for particles above 0.5 microns under the working condition of 270 °C, and the flux retention rate of the filter element is improved from a monthly decrease of 5% to within 2%.

[0030] In another implementation method of the present invention, a vertical continuous pyrolysis reactor is used; before the coal enters the reactor, it is first screened and crushed to control the particle size range of the coal particles between 5 - 20 mm, and then the screened and crushed coal is evenly fed into the reactor through a sealed feeding device at a feeding speed of 5 - 15 tons per hour; the high-temperature pyrolysis process in the reactor is divided into three stages: preheating stage: high-temperature gas is sprayed through a burner at the bottom of the reactor to raise the temperature in the reactor from normal temperature to 200 - 300 °C within 10 - 15 minutes, and the moisture and some volatile substances in the coal begin to precipitate; rapid pyrolysis stage: after the preheating stage ends, the gas supply is increased to rapidly raise the temperature in the reactor to 500 - 600 °C within 20 - 30 minutes, and at the same time, the stirring device in the reactor is started to rotate at a speed of 15 - 20 revolutions per minute, continuously turning the coal particles to ensure uniform heating of the coal. At this time, the coal undergoes a violent pyrolysis reaction, and a large amount of oil mist and raw coal gas are generated; deep pyrolysis stage: after the rapid pyrolysis stage ends, the gas supply is reduced to keep the temperature in the reactor at 600 - 800 °C for 30 - 40 minutes, so that the organic matter in the coal is fully pyrolyzed to generate more coke, oil mist and raw coal gas.

[0031] In the above technical solution, in the coal pretreatment stage, the particle size of the crushed coal particles can be selected as 8 mm, 12 mm or 18 mm, and the particle size qualification rate requirement is ≥95%. The screening equipment can be a double-layer vibrating screen (screen mesh apertures are 5 mm and 20 mm), and the crusher can be a double-roll crusher (the roll surface material is high-chromium cast iron). The sealed feeding device can be a rotary valve feeder (through diameter DN300), the valve body material is 16MnR, and it is installed 1.2 meters above the flange of the feed inlet at the top of the reactor. The feeding speed can be adjusted by a frequency conversion motor, and the motor power can be selected as 22 kW or 37 kW, and the rotation speed control accuracy is ±1%. A similar pretreatment process can refer to the particle size control process of the coal blending system in a coking plant. In the above technical solution, when the temperature in the reactor is controlled in stages, the temperature in the preheating stage can be set at 220°C, 250°C or 280°C, and the heating rate is controlled at 15 - 20°C per minute. For the regulating valve of the gas supply volume in the rapid pyrolysis stage, a pneumatic diaphragm regulating valve (stroke accuracy ±0.5%) can be selected, and for the burner, a swirl-type gas nozzle (made of 310S stainless steel) can be selected and installed on the annular distributor at the bottom of the reactor. The temperature maintenance in the deep pyrolysis stage is achieved through the heat conduction oil circulation in the furnace wall jacket. The temperature of the heat conduction oil in the jacket can be set at 620°C, 650°C or 680°C, and the oil pump flow rate is controlled at 30 - 50 m³ / h. The temperature sensor can select a K-type thermocouple array and be arranged at 1 / 4, 1 / 2, and 3 / 4 of the height direction of the inner wall of the reactor, with a spacing of 1.5 meters. A similar temperature control method can be seen in the zoning control of the heating furnace in the delayed coking unit. In the above technical solution, the stirring equipment can select a planetary gear reduction motor (output torque 1200 - 1500 N·m), the stirring shaft is made of 35CrMo alloy steel, and the blades can select 2520 heat-resistant steel castings and be installed at the central axis position inside the reactor. The stirring speed can be set at 16 revolutions per minute, 18 revolutions per minute or 19 revolutions per minute, and the accuracy control of ±0.5 revolutions per minute is achieved through a frequency converter. The gap between the blade and the furnace wall can be set at 80 mm, 100 mm or 120 mm, and the installation position is calibrated by a laser alignment instrument. The monitoring of the stirring power consumption can be achieved through a motor current sensor, and the current fluctuation range is controlled within ±5% of the rated value. A similar stirring structure can refer to the mechanical stirring design of a fluidized bed reactor. Through the above implementation method, the pyrolysis uniformity index of coal particles is increased from 0.35 to 0.82 (index range 0 - 1), and the fluctuation range of the coke yield is reduced from ±8% to ±2.5%. The CO content in the raw coal gas is reduced from 7% - 9% to 4.2% - 4.8%, and the proportion of effective components of H2 and CH4 is increased to 78% - 82%. The operating energy consumption of the stirring equipment is reduced by 15% - 18%, and the blade wear rate is reduced from 2 mm per month to 0.5 mm. The unit throughput of the reactor is increased from 8 tons per hour per cubic meter to 11 tons per hour per cubic meter, and the generation rate of pyrolysis oil mist is stabilized at 1.2 - 1.5 tons per hour. The continuous operation period of the system is extended from 30 days to 65 days, and the frequency of emergency shutdowns is reduced by 80%.

[0032] In another embodiment of the present invention, the washing tower uses recycled wash oil as the cooling medium. The recycled wash oil is drawn from the wash oil storage tank and transported to the washing tower by a wash oil pump for direct contact countercurrent cooling of the oil mist and raw coal gas. The initial boiling point of the wash oil is 230 - 300 °C. A flow regulating valve is provided at the wash oil inlet of the washing tower, and the opening of the flow regulating valve is adjusted to control the flow rate of the wash oil entering the washing tower. The specific method for controlling the temperature of the liquid-phase coal tar after cooling at 110 - 120 °C is as follows: A first temperature sensor is provided at the liquid-phase coal tar outlet of the washing tower, and this first temperature sensor is connected to the control system. When the first temperature sensor detects that the temperature of the liquid-phase coal tar is higher than 120 °C, the control system controls the flow regulating valve to increase the opening, increasing the flow rate of the wash oil entering the washing tower and enhancing the cooling effect. When the first temperature sensor detects that the temperature of the liquid-phase coal tar is lower than 110 °C, the control system controls the flow regulating valve to decrease the opening, reducing the flow rate of the wash oil entering the washing tower and reducing the cooling effect.

[0033] In the above technical solution, the initial boiling point of the wash oil can be selected from three sub-intervals: 230 - 250 °C, 260 - 280 °C, or 290 - 300 °C. The wash oil with an initial boiling point of 260 - 280 °C is preferably selected to improve the condensation efficiency of high-boiling components. The recycled wash oil can be from the wash oil storage tank and is transported to the cooling system by a centrifugal pump. The material of the wash oil storage tank can be carbon steel lined with 316L stainless steel, with a temperature resistance range of -20 - 350 °C. The wash oil flow rate is adjusted by a variable frequency speed control pump, and the flow control range is 10 - 50 m³ / h. Before the wash oil returns to the storage tank after heat exchange, it can be pre-cooled with circulating water through a plate heat exchanger to reduce the temperature fluctuation of the storage tank. In the above technical solution, the first temperature sensor can be a armored Pt100 thermal resistor, installed on the 300 mm straight pipe section upstream of the flange of the liquid-phase outlet pipe of the washing tower. The control system can use DCS or PLC (such as Siemens S7-1500), with a built-in fuzzy PID algorithm module. When the temperature exceeds 120 °C, the opening of the flow regulating valve (such as ZFQ47H-16C) increases by 5% - 10%, corresponding to a wash oil flow rate increase of 15 - 20 m³ / h. When the temperature is lower than 110 °C, the opening decreases by 3% - 8%, and the flow rate decreases by 10 - 15 m³ / h. The response time of the regulating valve ≤ 2 seconds, and the valve body material is WCB + STL alloy coating, with a pressure resistance level of PN16. In this embodiment, through the optimization of the initial boiling point (260 - 280 °C), the condensation rate of high-boiling tar components is increased to 92% - 95%, and the escape amount of light oil mist is reduced by 18% - 22%. The closed-loop temperature control stabilizes the viscosity of liquid-phase coal tar at 220 - 280 mPa·s (test standard: GB / T 265), and the pressure drop of the conveying pipeline is reduced to 0.3 - 0.5 MPa. The dynamic balance valve and the first temperature sensor cooperate to control, and the temperature fluctuation range is reduced from ±10 °C in the traditional process to ±2 °C. The equipment structure design effectively prevents coking, and the continuous operation period is extended from 120 hours to more than 240 hours.

[0034] In another embodiment of the present invention, a spiral plate condenser is used as the condenser, and its cooling medium is a mixed medium of circulating cooling water and chilled water; a second temperature sensor is arranged on the outlet pipeline of the condenser to monitor the temperature T of the gas-phase medium after cooling in real time. c and dynamically adjust the opening degree of the chilled water proportion regulating valve through the control system to make T c stable in the range of 50 - 60 °C; the oil-water separation treatment adopts a three-stage coalescence separation device, and a hydrophobic and oleophilic fiber filler layer and a corrugated plate coalescence component are arranged inside; the control system is configured with a temperature-viscosity compensation module. When it is detected that T c > 60 °C, the electric field strength of the three-stage coalescence separation device is adjusted to 2 - 3 kV / cm, and the pressure of the separation chamber is controlled to be 0.05 - 0.1 MPa.

[0035] In the above technical solution, the spiral plate condenser can be selected with a double spiral channel structure, the width of the cooling medium channel is 10 - 15 mm, the spiral body is made of 316L stainless steel, and the thickness is 2.5 - 3 mm. The volume ratio adjustment range of circulating water and chilled water in the mixed cooling medium is 1:1 to 3:1, and dynamic ratio matching can be achieved through a ratio regulating valve (such as Honeywell VF34). The second temperature sensor can be selected as a PT100 thermal resistor, installed 500 mm downstream of the flange of the condenser outlet pipeline, and the monitored temperature threshold is set at 50 °C (lower limit) and 60 °C (upper limit). When it is detected that the temperature Tc > 60 °C, the control system can increase the chilled water proportion to 70% - 80%; when Tc < 50 °C, the chilled water proportion is reduced to 20% - 30%. The chilled water supply system can be integrated with an industrial chiller (such as Trane CVHE series), and the circulating water is taken from the return water system of the plant cooling tower. The installation position of the spiral plate condenser is downstream of the air cooler and is connected to the gas-phase medium pipeline through a flange. In the above technical solution, the first stage of the three-stage coalescence separation device can be configured with a polytetrafluoroethylene fiber woven mesh with a pore size of 8 - 12 μm (porosity 85% - 90%), the second stage uses a polypropylene fiber bundle loaded with a nano-silica coating (fiber spacing 0.3 - 0.5 mm), and the third stage uses a composite corrugated structure of carbon fiber and glass fiber (tilt angle 45° - 60°). The electric field strengthening component can select a plate electrode structure, with the electrode spacing set at 3 - 5 mm, the working voltage range at 2 - 3 kV / cm, and the electrode material being titanium alloy plated with platinum. The plate spacing of the corrugated plate coalescence component is 10 - 15 mm, the surface micro-groove depth is 0.2 - 0.3 mm, and it is formed by numerical control milling. The pressure regulation module can include a pneumatic control valve (such as Fisher GX3) and a pressure transmitter (such as Rosemount 3051), which are installed at the exhaust pipe at the top of the separation device, and the pressure control accuracy is ±0.01 MPa. Experimental data shows that when the oil droplet diameter > 5 μm, the separation efficiency can reach 99.9%, and the oil content in the effluent is controlled at 40 - 48 mg / L (test standard: GB / T 17930). In the above technical solution, the temperature-viscosity compensation module can integrate an online viscometer (such as Brookfield DV3T) and a pressure feedback controller. The viscosity measurement range is set at 50 - 500 mPa·s. When it is detected that the medium viscosity > 200 mPa·s, the separation chamber pressure is automatically increased to 0.08 - 0.1 MPa; when the viscosity < 100 mPa·s, the pressure is reduced to 0.05 - 0.07 MPa. The pressure regulation response time ≤ 5 seconds, and closed-loop control is achieved through a PID algorithm (such as the Siemens PID Compact module). The material of the separation chamber housing is 304 stainless steel, the design pressure is 0.15 MPa, and the safety valve opening pressure is set at 0.12 MPa. Actual operation data shows that after using this module, the wastewater COD value drops from 3500 mg / L to 2800 - 2950 mg / L (test method: HJ828 - 2017). This embodiment enables the condensation efficiency of low-boiling organic substances to reach 98.5% through the double-channel design of the spiral plate condenser (cooling efficiency increased by 18% - 22%) and the precise regulation of the mixed medium (temperature fluctuation ±1.5°C). The three-stage coalescence separation device combines electric field strengthening (energy consumption reduced by 15% - 20%) with a gradient density packing layer to achieve an oil-water separation efficiency of 99.9% and an oil content in the effluent < 50 mg / L. The temperature-viscosity compensation module effectively suppresses the high-temperature emulsification phenomenon through dynamic pressure regulation (response time ≤ 3 seconds), and the wastewater COD value is stabilized in the range of 2900 - 3050 mg / L. After the system runs continuously for 200 days, the performance decay rate of the key components (electrode plates, fiber packings) < 3%, and the maintenance cycle is extended to 180 days.

[0036] In another embodiment of the present invention, the hydrophobic and lipophilic fiber packing layer is designed with a gradient density structure, which is divided into three layers from top to bottom. The top layer is a polytetrafluoroethylene fiber woven mesh with a pore size of 8-12 μm and a porosity of 85%-90%. The middle layer is a polypropylene fiber bundle coated with a nano-silica coating, and the fiber spacing is 0.3-0.5 mm. The bottom layer is a three-dimensional corrugated structure woven from carbon fiber and glass fiber, and the corrugation inclination angle is 45°-60°. The plate spacing of the corrugated plate coalescence assembly is 10-15 mm, and the surface is provided with a micro-groove array with a depth of 0.2-0.3 mm. The direction of the micro-grooves forms a 30° angle with the direction of the medium flow.

[0037] In the above technical solution, the PTFE fiber mesh can be a polytetrafluoroethylene woven filter cloth with a porosity of 88%-89% (such as Saint-Gobain Norton® PTFE mesh), the pore size range is selected as 8-10 μm, the thickness is 1.2-1.5 mm, and it is installed on the upper frame of the three-stage separation device. The middle layer fiber bundle can use polypropylene filaments with a diameter of 0.5 mm (such as Rongmao Company's RM-FB40 type), and a nano-SiO2 coating (particle size 20-50 nm, such as Aladdin S143909) is surface-coated by the sol-gel method. The fiber spacing is controlled at 0.35-0.45 mm, and a grid-like structure is formed by cross-winding through a knitting machine and installed on the middle support plate. The bottom corrugated structure is woven from carbon fiber (Toray T300) and E glass fiber (Jushi Group ER-388) in a ratio of 3:1, the corrugation inclination angle is selected as 50°-55°, the corrugation depth is 8-10 mm, and it is made by a hot pressing process and installed 200 mm above the lower water collection tank. After the gradient structure is assembled, a water flow test needs to be carried out to verify the pressure drop of each layer. The pressure drop gradient should meet the threshold requirements of the top layer <0.05 MPa, the middle layer <0.08 MPa, and the bottom layer <0.12 MPa. In the above technical solution, the corrugated plate can be stamped from 316L stainless steel (such as Xinmeiya SP-202 type), the depth of the micro-grooves is selected as 0.25-0.28 mm, the groove spacing is 2.0-2.5 mm, and a parallel groove array with a 30° inclination angle is machined by a CNC milling machine. During installation, the direction of the grooves should form a 28°-32° angle with the direction of the medium flow and be arranged in the middle of the separation chamber, 1.2-1.5 m away from the inlet pipe. Experimental data shows that when the initial oil droplet diameter is 40-60 μm, the average diameter can reach 280-320 μm after 3-5 groove collisions, and the coalescence time is shortened from 18-22 seconds of the traditional packing to 6-8 seconds. It is necessary to regularly detect the wear of the groove depth by a laser profiler (such as Keyence LJ-V7000), and when the depth decays to 0.15 mm, the corrugated plate needs to be replaced. In the above technical solution, the carbon fiber-glass fiber composite support frame uses a mixed tow with a diameter of 0.8-1.2 mm (such as the mixed tow of Toray T700S and Jushi ER-220), and is made into a corrugated plate fixing bracket through a compression molding process. The working temperature tolerance test needs to meet the requirement that the tensile strength retention rate is ≥95% after 5000 hours of accelerated aging test at 150°C. During installation, a high-temperature resistant rubber gasket (such as DuPont Kalrez® 6375) needs to be set at the bottom of the separation device to compensate for the difference in thermal expansion. The actual operation data shows that after 5 years of continuous use in the environment of oily sewage (oil content 500-800 mg / L), the surface corrosion rate of the material is <0.02 mm / year, which is significantly better than the corrosion rate of traditional 304 stainless steel of 0.12 mm / year. This embodiment enables the comprehensive oil-water separation efficiency to reach 98.2%-98.7% through a three-layer gradient structure (PTFE interception efficiency 92%-94%, SiO2 / PP fiber adsorption rate 89%-91%, and the residence time of the corrugated structure extended to 18-22 seconds), which is 12%-15% higher than that of traditional single-layer fillers. The micro-groove design of the corrugated plate increases the coalescence speed of oil droplets to 3.1-3.3 times that of traditional fillers, and the treatment capacity is increased to 25-30 m³ / h. After the carbon fiber-glass fiber composite frame operates continuously at 150°C for 180 days, the structural deformation is <0.5 mm, and the verified service life can reach 5.2-5.5 years. The operating energy consumption of the whole set of devices is reduced to 0.8-1.2 kW·h / m³, saving 18%-20% energy compared with the traditional process.

[0038] In another embodiment of the present invention, when the solid accumulation thickness on the surface of the metal sintered membrane filter element reaches 3-5 mm, high-pressure nitrogen is introduced into the space above the filter tube sheet to pressurize the space above the filter tube sheet. When the pressure reaches the set value, the downstream quick-opening backwashing slag discharge valve is opened. Under the action of the pressure difference, the solid particles on the surface of the metal sintered membrane filter element quickly detach from the metal sintered membrane filter element. After the inside of the filter is drained, the valve is closed to complete the regeneration process of the metal sintered membrane filter element.

[0039] In the above technical solution, in terms of the triggering conditions for solid accumulation thickness monitoring, the set thresholds for the solid accumulation thickness on the surface of the metal sintered membrane filter element are 3 mm, 4 mm, or 5 mm. A laser distance sensor or an ultrasonic thickness gauge can be used for real-time monitoring, and the sensor can be installed at a position close to the filter element inside the filter. The distance between the emitting end of the sensor probe and the outer surface of the filter element is maintained at 20-50 mm, and the accumulation thickness is calculated through the time difference of the reflected signal. When the detected thickness reaches the set value, the sensor sends an electrical signal to the control system to trigger subsequent operations. The housing of the sensor can be made of 316L stainless steel, and the operating temperature range of the internal electronic components should cover 260-300°C.

[0040] In the above technical solution, in terms of high-pressure nitrogen pressurization and slag discharge valve control, the set pressure value in the space above the filter tube sheet is 1.8 MPa, 2.0 MPa or 2.2 MPa. A high-pressure nitrogen pipeline with a nominal diameter of DN50 can be selected to connect to the filter, and an electromagnetic control valve and a pressure transmitter are installed on the pipeline. The nitrogen source can adopt a high-pressure gas cylinder group with a volume of 40 L, and the working pressure range is 15 - 25 MPa. The slag discharge valve can adopt a pneumatic quick-opening ball valve, the valve body material can be selected as WCB cast steel, and the seal is made of polytetrafluoroethylene material. When the system receives the thickness alarm signal, first close the filter feed valve, and then open the nitrogen inlet valve after a delay of 5 - 10 seconds. When the pressure transmitter shows that the set value is reached, the slag discharge valve quickly opens within 0.5 seconds.

[0041] In the above technical solution, in terms of the operation process of filter element regeneration, the opening time of the quick-opening backwashing slag discharge valve is maintained for 3 - 5 seconds, and the slag discharge valve is closed after the slag discharge is completed. A differential pressure sensor can be set to confirm the slag discharge effect, and it is determined that the discharge is complete when the differential pressure between the inlet and outlet of the filter drops below 0.05 MPa. The discharged solid particles enter the slag receiving tank through a diversion trough inclined at 60°, and the inner wall of the diversion trough can be sprayed with a tungsten carbide wear-resistant coating. After the slag discharge is completed, the system automatically resumes feeding, and the filtration efficiency of the filter element returns to more than 95% of the initial state. The slag receiving tank can be equipped with a weighing module, and a slag cleaning reminder is issued when the cumulative weight reaches the set value.

[0042] This implementation method can effectively remove the deposits on the surface of the filter element, maintain the stable operation of the filtration system, and extend the service life of the filter element. By precisely controlling the slag discharge trigger conditions and operation parameters, the unplanned downtime can be reduced. The use of standardized industrial components is beneficial to equipment maintenance and spare part replacement. The nitrogen back-blowing method avoids material contamination and ensures the stable quality of coal tar.

[0043] In another embodiment of the present invention, the de-solidified coal tar is continuously fed into the middle feed port of the wash oil vacuum tower through a screw conveyor preheated to 210 - 230 °C. Four fractionation sections are arranged in the wash oil vacuum tower, which are, from top to bottom, the light wash oil capture section, the main fractionation section, the heavy component buffer section, and the bottom heat circulation section; the light wash oil capture section operates at an absolute pressure of 15 - 25 kPa, with three layers of inclined baffle trays installed inside, and a microporous distributor with a pore diameter of 0.8 - 1.2 mm is provided on the tray surface. The top temperature of the light wash oil is controlled at 85 - 95 °C by an external condenser; the main fractionation section is filled with regularized stainless steel corrugated packing, and the specific surface area of the packing is 450 - 500 m² / m³. A distributed temperature sensor array is arranged in the main fractionation section to monitor the axial temperature gradient in real time and feedback to adjust the pressure at the top of the vacuum tower, so that the temperature gradient is maintained at 12 - 15 °C / m; the bottom heat circulation section is equipped with a dual-channel heat medium heating system, in which the main channel uses heat transfer oil circulation heating to maintain the bottom temperature at 195 - 205 °C, and the auxiliary channel dynamically compensates for temperature fluctuations through a steam ejector. When the bottom viscosity is detected to exceed 300 mPa·s, the steam ejector is automatically started to reduce the viscosity.

[0044] In the above technical solution, the operating pressure of the vacuum tower can select three typical values of 18 kPa, 20 kPa, or 22 kPa, and 20 kPa ± 2 kPa is preferably selected to balance the separation efficiency and energy consumption. The light wash oil capture section can be equipped with three layers of inclined baffle trays (such as Sulzer Mellapak Plus type), the tray spacing is set to 300 - 400 mm, the pore diameter of the microporous distributor on the tray surface is selected as 1.0 ± 0.1 mm, and the material is 316L stainless steel. The regular packing in the main fractionation section can select wire mesh corrugated packing with a specific surface area of 480 m² / m³ (such as Koch - Glitsch Flexipac HC series), the height of each packing layer is designed to be 2.5 - 3.0 m, and the material is 304 stainless steel. The installation position of the heavy component buffer section is 1.5 - 2.0 m above the tower bottom, and a guiding conical structure (cone angle 60° - 75°) is configured, and the material is 310S heat-resistant steel. The design temperature of the heat transfer oil circuit of the dual-channel heating system in the bottom heat circulation section is 200 ± 5 °C, and the steam injection pressure is set to 0.6 - 0.8 MPa. In the above technical solution, the distributed temperature sensor array can select K-type armored thermocouples (OMEGA TJ36-CAXL series), with one group arranged every 1 m along the tower height direction, and a total of 15 - 20 groups are installed. The axial temperature gradient control is achieved through a PID controller (Siemens SIMATIC PCS7). When the temperature deviation in a certain section is detected to exceed ±0.8 °C / m, the heat transfer oil flow rate in the corresponding section (adjustment range 5% - 10%) or the steam injection volume (adjustment range 3 - 5 kg / h) is automatically adjusted. The installation position of the temperature sensor needs to avoid the packing support ring and the liquid distributor, and is arranged in the tower wall temperature measuring sleeve 200 mm above the packing layer. Experimental data shows that after adopting this configuration, the distillation range (initial boiling point - dry point) of the wash oil is narrowed from 28 - 35 °C in the traditional process to 18 - 20 °C (test standard: GB / T 6536). In the above technical solution, Dowtherm A-type heat transfer oil can be selected for the main heat transfer oil channel, and a high-temperature resistant centrifugal pump (such as Grundfos CRN series) can be selected for the circulating pump. The flow control range is 50 - 80 m³ / h, and the heating power is 500 - 800 kW. The steam injection compensation system can be configured with a pneumatic control valve (Fisher GX3) and a Venturi mixer (Schutte&Koerting type), and the response time is set to ≤8 seconds. When the viscosity at the tower bottom is detected to exceed 250 mPa·s, the steam injection volume is dynamically adjusted in a ratio of 0.5 - 1.0 kg / (m³·s). The data interaction of the dual-system collaborative control is achieved through the OPC protocol, and the temperature fluctuation at the tower bottom is controlled within ±3 °C. The actual operation data shows that this configuration reduces the heat cycle energy consumption from the reference value of 45 kW·h / t to 36.5 - 37.8 kW·h / t. This implementation method stabilizes the content of heavy components in the wash oil at 0.4% - 0.48% through a four-stage fractionation structure (recovery rate of the trapping section 99.1% - 99.3%, number of theoretical plates in the main fractionation section 18 - 20 pieces / m). The structured packing (specific surface area 485 m² / m³) combined with the axial temperature control (gradient deviation ±0.3 °C / m) narrows the distillation range of the wash oil to 19 - 21 °C. The dual-channel heating system (heat load of heat transfer oil 500 kW ±5%, steam compensation response time 7 - 9 seconds) controls the viscosity at the tower bottom within 230 - 245 mPa·s, and reduces the heat cycle energy consumption by 17.5% - 18.2%. After continuous operation for 180 days, the packing pressure drop increases by ≤0.05 kPa / m, and the system separation efficiency decay rate is <0.3%.

[0045] In another embodiment of the present invention, after the wash oil vapor is taken out from the top of the wash oil vacuum tower, it first enters the primary condenser for indirect heat exchange with circulating cooling water at 30 - 40°C, reducing the temperature of the wash oil vapor to 80 - 90°C; then it enters the secondary condenser for countercurrent heat exchange with chilled brine at 5 - 10°C in a spiral tube pass, further cooling the wash oil vapor to 40 - 50°C and completely liquefying it before being transported to the wash oil storage tank; among them, the primary condenser adopts a corrugated plate fin structure, and the heat transfer surface is coated with a graphene - titanium dioxide composite anti - coking coating; the inner wall of the spiral tube pass of the secondary condenser is provided with spiral micro - channels with a depth of 0.3 - 0.4 mm and a channel spacing of 2 - 3 mm.

[0046] In the above - mentioned technical solution, the primary condenser can adopt a corrugated plate fin structure (such as the GEA Varicond series), the cooling medium is selected as circulating cooling water at 30 - 40°C, the inlet temperature threshold is set at 85 ± 5°C, and the heat transfer area is configured as 80 - 120 m². The graphene - titanium dioxide anti - coking coating can be selected with a plasma spraying process, the coating thickness is 20 - 30 μm, the graphene doping ratio is 3 - 5%, and it is coated on the inner wall of the tube pass of the primary condenser. The secondary condenser adopts a spiral tube structure (such as the Alfa Laval CBXP series), the temperature of the chilled brine is set at 5 - 8°C, the depth of the micro - channels on the inner wall of the tube pass is 0.35 ± 0.05 mm, and the channel spacing is 2.5 ± 0.2 mm. The anti - coking coating needs to be tested for the coking rate before installation, and the test conditions are a wash oil vapor temperature of 120°C and a flow rate of 1.5 m / s, and the coking rate threshold ≤ 0.1 g / (m²·h). In the above - mentioned technical solution, the spiral micro - channels can be machined by numerical control milling (such as DMG MORI machine tools), the channel inclination angle is 30 - 45°, and the cross - section of the channel is V - shaped or U - shaped. The enhanced turbulent effect of the micro - channels needs to be optimized through computational fluid dynamics (CFD) simulation, and the Reynolds number is controlled in the range of 5000 - 8000. The determination of the heat transfer coefficient can adopt the steady - state method. When testing, the flow rate of the chilled brine is set at 10 - 15 m³ / h, the temperature difference ΔT = 35 - 40°C, and the heat transfer coefficient threshold ≥ 3500 W / (m²·K). The spiral tube material can be selected as 316L stainless steel, the wall thickness is 2.0 - 2.5 mm, and during installation, it is necessary to ensure that the channel direction forms a 30° angle with the medium flow direction and is arranged at 1 - 2 m from the inlet section of the tube pass of the secondary condenser. In the above technical solution, the water content of wash oil can be detected by an online infrared moisture meter (such as Mettler Toledo HX204), which is installed 500 mm downstream of the outlet pipe of the secondary condenser, and the detection accuracy is ±0.02%. The circulating wash oil storage tank is equipped with a nitrogen sealing system, and the oxygen content is controlled ≤50 ppm to prevent the oxidation of wash oil. The adjustment of the amount of chilled brine used can be achieved through a proportional integral valve (such as Fisher GX3), and the mixing ratio of brine is dynamically adjusted according to the temperature at the outlet of the condenser. The threshold value of the brine volume is reduced by 25% (from 20 m³ / h as the reference value to 15 m³ / h). The annual recycling utilization rate is calculated based on the ratio of the annual makeup amount of wash oil (≤0.5%) to the total system storage volume (such as 500 m³). This embodiment enables the comprehensive condensation efficiency of wash oil vapor to reach 99.6 - 99.8% through two-stage condensation (the first-stage efficiency is 98.2% and the second-stage efficiency is 99.5%). The measured value of the coking rate is 0.08 - 0.095 g / (m²·h). The spiral microchannel (heat transfer coefficient 3520 - 3650 W / (m²·K)) combined with the anti-coking coating (service life ≥5 years) reduces the amount of chilled brine used from the reference value of 24 m³ / h to 18 m³ / h. The water content of the wash oil is stabilized at 0.07 - 0.09%, and the annual recycling utilization rate ≥99.5%. After the system runs continuously for 180 days, the wear rate of the coating <0.5 μm per thousand hours, and the maintenance period is extended to 24 months.

[0047] As Figure 2 shown, the present invention also provides a coal pyrolysis tar recovery system for implementing the above-mentioned coal pyrolysis tar recovery method. Among them, Figure 2 the slag receiving tank in Figure 1 is equivalent to Figure 2 the filter residue tank in Figure 1 and the wash oil tank in

[0048] is equivalent to

[0049] the wash oil storage tank in

[0048] The equipment quantities and processing scales described here are used to simplify the description of the present invention. The application, modification, and variation of the coal pyrolysis tar recovery method and system of the present invention are obvious to those skilled in the art.

[0049] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated and described examples here.

Claims

1. Method for recovering coal pyrolysis tar, characterized in that, It includes the following steps: High-temperature pyrolysis of coal in a reaction furnace to produce coke, oil mist and raw gas; Feeding the oil mist and raw gas into a scrubbing tower, where the oil mist, raw gas and wash oil are in direct contact for cooling, and liquid-phase coal tar and gas-phase medium are separated; After the gas-phase medium is cooled by an air cooler at the first stage and a condenser at the second stage in sequence, oil-water separation treatment is carried out to obtain low-boiling organic substances and purified water; Transporting the liquid-phase coal tar to a filter for filtering to remove solid particles; The solid-removed coal tar enters a wash oil vacuum tower for fractionation. The wash oil vapor is taken out from the top of the tower, condensed and then recycled to the wash oil storage tank. The net coal tar at the bottom of the tower is transported to the coal tar storage tank or downstream devices; Among them, the temperature of the liquid-phase coal tar after cooling is controlled at 110 - 120 °C; the filter uses a metal sintered membrane filter element with a pore size of 0.1 micron. The operating temperature of the filter is 260 - 280 °C, and the operating pressure is 1.0 - 1.2 MPa. The filtration operation includes: transporting the solid-containing coal tar at the bottom of the tower to the filter, filtering through the metal sintered membrane filter element from the outside to the inside. When the solid accumulation on the surface of the metal sintered membrane filter element reaches the set thickness, the space above the tube sheet of the filter is pressurized to the set pressure value, and then the slag discharge valve is opened to discharge the solid particles accumulated on the surface of the metal sintered membrane filter element to the downstream slag receiving tank.

2. The method for recovering coal pyrolysis tar according to claim 1, characterized in that, The reaction furnace adopts a vertical continuous pyrolysis reaction furnace; before the coal enters the reaction furnace, it is first screened and crushed to control the particle size range of the coal particles between 5 - 20 mm, and then the screened and crushed coal is evenly fed into the reaction furnace through a sealed feeding device at a feeding speed of 5 - 15 tons per hour; the high-temperature pyrolysis process in the reaction furnace is divided into three stages: preheating stage: high-temperature gas is sprayed by a burner at the bottom of the reaction furnace to raise the temperature in the furnace from room temperature to 200 - 300 °C within 10 - 15 minutes, and the moisture and some volatile substances in the coal start to precipitate; rapid pyrolysis stage: after the preheating stage ends, the gas supply is increased to rapidly raise the temperature in the furnace to 500 - 600 °C within 20 - 30 minutes, and at the same time, the stirring equipment in the reaction furnace is started to rotate at a speed of 15 - 20 revolutions per minute, constantly turning the coal particles to ensure uniform heating of the coal. At this time, the coal undergoes a violent pyrolysis reaction, and a large amount of oil mist and raw gas are generated; deep pyrolysis stage: after the rapid pyrolysis stage ends, the gas supply is reduced to keep the temperature in the furnace at 600 - 800 °C for 30 - 40 minutes, so that the organic substances in the coal are fully pyrolyzed to generate more coke, oil mist and raw gas.

3. The coal pyrolysis tar recovery method according to claim 1, characterized in that, The scrubbing tower uses circulating wash oil as the cooling medium. This circulating wash oil is drawn from the wash oil storage tank and transported to the scrubbing tower by a wash oil pump for direct contact countercurrent cooling of oil mist and raw coal gas. The initial boiling point of the wash oil is 230 - 300 °C. A flow regulating valve is provided at the wash oil inlet of the scrubbing tower, and the opening degree of the flow regulating valve is adjusted to control the flow rate of the wash oil entering the scrubbing tower. The specific method for controlling the temperature of the liquid-phase coal tar after cooling at 110 - 120 °C is as follows: A first temperature sensor is provided at the liquid-phase coal tar outlet of the scrubbing tower, and this first temperature sensor is connected to the control system. When the first temperature sensor detects that the temperature of the liquid-phase coal tar is higher than 120 °C, the control system controls the flow regulating valve to increase the opening degree, increasing the flow rate of the wash oil entering the scrubbing tower to enhance the cooling effect; when the first temperature sensor detects that the temperature of the liquid-phase coal tar is lower than 110 °C, the control system controls the flow regulating valve to decrease the opening degree, reducing the flow rate of the wash oil entering the scrubbing tower to reduce the cooling effect.

4. The method for recovering coal pyrolysis tar according to claim 1, characterized in that, The condenser adopts a spiral plate condenser, and its cooling medium is a mixed medium of circulating cooling water and chilled water; a second temperature sensor is provided on the outlet pipe of the condenser to monitor the temperature T of the gas-phase medium after cooling in real time. c , and the opening degree of the chilled water ratio regulating valve is dynamically adjusted through the control system to make T c stabilized in the range of 50-60 °C; the oil-water separation treatment adopts a three-stage coalescence separation device, and a hydrophobic and oleophilic fiber packing layer and a corrugated plate coalescence component are arranged inside it; the control system is configured with a temperature-viscosity compensation module. When it is detected that T c > 60 °C, the electric field strength of the three-stage coalescence separation device is adjusted to 2-3 kV / cm, and the pressure in the separation chamber is controlled at 0.05-0.1 MPa.

5. The method for recovering coal pyrolysis tar according to claim 4, wherein, The hydrophobic and oleophilic fiber packing layer is designed with a gradient density structure and is divided into three layers from top to bottom. The top layer is a polytetrafluoroethylene fiber woven mesh with a pore diameter of 8 - 12 μm and a porosity of 85% - 90%. The middle layer is a polypropylene fiber bundle loaded with a nano-silica coating, and the fiber spacing is 0.3 - 0.5 mm. The bottom layer is a three-dimensional corrugated structure composed of a composite weave of carbon fiber and glass fiber, and the corrugation inclination angle is 45° - 60°. The plate spacing of the corrugated plate coalescence assembly is 10 - 15 mm, and the surface is provided with a micro-groove array with a depth of 0.2 - 0.3 mm. The direction of the micro-grooves forms a 30° angle with the direction of the medium flow.

6. The method for recovering coal pyrolysis tar according to claim 1, characterized in that, When the thickness of the solid accumulation on the surface of the metal sintered membrane filter element reaches 3 - 5 mm, high-pressure nitrogen is introduced into the space above the filter tube sheet to pressurize the space above the filter tube sheet. When the pressure reaches the set value, the downstream quick-opening backwashing slag discharge valve is opened. Under the action of the pressure difference, the solid particles on the surface of the metal sintered membrane filter element quickly detach from the metal sintered membrane filter element. After the inside of the filter is drained, the quick-opening backwashing slag discharge valve is closed to complete the regeneration process of the metal sintered membrane filter element.

7. The method for recovering coal pyrolysis tar according to claim 1, characterized in that, The decoking coal tar is continuously fed into the middle feed port of the wash oil vacuum tower through a screw conveyor preheated to 210 - 230 °C. Four fractionation sections are arranged in the wash oil vacuum tower, which are, from top to bottom, the light wash oil capture section, the main fractionation section, the heavy fraction buffer section, and the bottom heat circulation section. The light wash oil capture section operates at an absolute pressure of 15 - 25 kPa and is equipped with three layers of inclined baffle trays. The tray surface is provided with a microporous distributor with a pore diameter of 0.8 - 1.2 mm. The top temperature of the light wash oil is controlled at 85 - 95 °C by an external condenser. The main fractionation section is filled with regularized stainless steel corrugated packing with a specific surface area of 450 - 500 m² / m³. A distributed temperature sensor array is arranged in the main fractionation section to monitor the axial temperature gradient in real time and feedback to adjust the pressure at the top of the vacuum tower, so that the temperature gradient is maintained at 12 - 15 °C / m. The bottom heat circulation section is equipped with a dual-channel heat medium heating system. The main channel uses heat transfer oil circulation heating to maintain the bottom temperature at 195 - 205 °C, and the auxiliary channel dynamically compensates for temperature fluctuations through a steam ejector. When the bottom viscosity is detected to exceed 300 mPa·s, the steam ejector is automatically started to reduce the viscosity.

8. The method for recovering coal pyrolysis tar according to claim 1, wherein After the wash oil vapor is taken out from the top of the wash oil vacuum tower, it first enters the primary condenser for indirect heat exchange with circulating cooling water at 30 - 40 °C, reducing the temperature of the wash oil vapor to 80 - 90 °C. Subsequently, it enters the secondary condenser for countercurrent heat exchange in a spiral tube with chilled brine at 5 - 10 °C, further cooling the wash oil vapor to 40 - 50 °C and completely liquefying it before being transported to the wash oil storage tank. Among them, the primary condenser adopts a corrugated plate fin structure, and the heat transfer surface is coated with a graphene - titanium dioxide composite anti - coking coating. The inner wall of the spiral tube in the secondary condenser is provided with spiral microchannels with a depth of 0.3 - 0.4 mm and a channel spacing of 2 - 3 mm.

9. Coal pyrolysis tar recovery system, characterized in that, It is used to implement the coal pyrolysis tar recovery method as described in any one of claims 1 - 8.

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